Machines used in earth moving, agricultural and construction applications are subjected to extreme wear. The moving components of such machines need to be provided with a constant supply of lubrication and do so while limiting the loss of that lubrication to the environment and inflow of debris from the worksite into the lubrication supply.
Two examples of such machines are track-type tractors and wheeled loaders. With a track-type tractor, a pair of continuous tracks are provided so as to provide locomotion to the machine. The tracks are trained around a plurality of drive sprockets and idlers with an engine of the machine rotating the drive sprockets. This in turn rotates the track over the sprockets and idlers. The track itself its comprised of a number of individual track shoes connected by track links. The track links are themselves connected through a plurality of bushings and track pins to allow for the track to pliably move around the sprockets and idlers while at the same time ensuring the structural integrity of the track remains in place. In such an embodiment, it can therefore be seen that the supply of lubrication to such track pins is of the utmost importance.
Another example is with respect to the aforementioned wheeled loader. With such a machine, a pair of boom arms are pivotally attached to the machine and are in turned pivotally connected to a bucket or other work implement. Alternatively, a secondary set of arms may be interposed between the boom arms and the work implement. Hydraulic cylinders powered by the engine of the machine allow for the movement of the arms and work implements. With each pivot or joint, however, a linkage pin needs to be provided to, in a manner similar to the aforementioned track-type tractor track pins, maintain the physical connections between the components while at the same time allowing for movement. Such linkage pins in turn require a continuous supply of lubrication as described above.
Over the years, a number of different configurations have been used in an attempt to provide such lubrication while preventing the loss of the lubrication and inflow of debris, e.g., dirt, dust, and moisture into the lubrication supply. For example, it is well known, such as in U.S. Pat. No. 4,560,174, to provide a lubrication cavity proximate such pins, with a seal assembly disposed within the lubrication cavity. The seal assembly itself can be provided in any number of different ways such as by providing a seal ring proximate to the pin, and a load ring positioned between a seal ring and the lubrication cavity so as to bias the seal ring toward the pin. The seal assembly components can be manufactured from flexible materials so as to allow a certain degree of play, but at the same time allow for direct contact between the components of the seal assembly, the lubrication cavity, and the pin, bushings, and/or spacers associated with the seal assembly.
With any of the aforementioned types of seal assemblies it is important for the load ring to maintain contact with the seal ring so as to accomplish all of the foregoing objectives, i.e., biasing the seal ring toward the pin, limiting outflow of lubricant, and preventing inflow of debris. Accordingly, it has been known to provide a number of different configurations for maintaining contact between the load ring and seal ring such as providing splines on one or both of the load ring and seal ring. In so doing, rotational translation between the two components is hopefully avoided. However, continuous improvement in such seal assemblies is always being sought and it is desirable to provide such a seal assembly which accomplishes all the foregoing objectives, while at the same time even further limiting the movement of the load ring relative to the seal ring in all directions.